1. Field of the Invention
This invention relates to shoe machines and more particularly to a shoe backpart portion molding machine.
2. Prior Art
Shoe backpart molding machines are used in shoe manufacture to draft or form the shoe upper lengthwise after insertion of a stiffener, to form and mold the heel portion thereof and to simultaneously wipe the lasting margin in the heel end region. The shoe upper is thus placed on a heated inner form with the counter inserted in the heel portion thereof. An arrangement of side pincers beneath the inner form grip the shoe upper, and a heated rubber outer form, which is arranged into support portions which are pivotable and inflatable, mold the backpart of the shoe upper. When the outer form is lowered, it first engages the upper and the inner form in the region of the back seam, then the support portions swing inwardly. After the closing operation, the support portions are inflated on their inside and thus press the outer mold to the tensioned upper.
Such a prior art shoe backpart molding machine has the disadvantage of having an outer mold which is liable to damage because of the unitary inflatable membrane contained therein. In practice this membrane can be sealed only with difficulty. The edges quickly wear out and break after a short period of time because they are pressed almost completely flat in the rest condition. The elements are difficult to mount and to maintain. The unitary hollow air cushion gives rise also to an unsatisfactory pressing of the upper on the inner form.
It is an object of the present invention to produce a backpart molding machine which is simple to produce, easier to assemble and maintain, and less liable to wear than the prior art backpart molding machines.